Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020
Deferred income tax assets:
Insurance liabilities		$ 50,316	$ 47,602
Pension liability		0	6,789
Operating lease liabilities		76,451	68,652
Deferred compensation		40,080	36,790
Accrued federal payroll taxes	[1]	14,235	27,428
Other (including liabilities and reserves)		31,252	29,816
Total deferred income tax assets		212,334	217,077
Valuation allowance for deferred tax assets		(2,465)	(3,856)
Net deferred income tax assets		209,869	213,221
Deferred income tax liabilities:
Goodwill and identifiable intangible assets		(154,382)	(146,821)
Operating lease right-of-use assets		(71,759)	(64,434)
Depreciation of property, plant and equipment		(25,341)	(23,958)
Pension asset		(1,847)	0
Other		(7,491)	(7,444)
Total deferred income tax liabilities		(260,820)	(242,657)
Net deferred income tax liabilities		$ (50,951)	$ (29,436)

[1] Represents employer Social Security tax payments deferred under the CARES Act.